Internal graft prosthesis and delivery system

ABSTRACT

A resilient tubular graft is delivered into place within a body passage by elongating the graft to reduce its diameter and then directing the graft to the desired position while in the elongated condition. The graft is carried into position by a pair of elongate members mounted for longitudinal movement relative to one other. Flexible lines secure opposite ends of the graft to the respective elongate members whereby relative longitudinal movement of the members functions to elongate the graft and reduce its diameter. The lines extend around the graft to impart radial compression thereto simultaneously with elongation of the graft. Upon placement of the graft at the desired location within a body passage, the lines are released to permit the graft to expand into engagement with the passage. Barbs on the graft provide for secure engagement of the graft with a body passage.

This is a Continuation of application Ser. No. 08/714,627, filed Sep.16, 1996, now abandoned, which is a continuation of application Ser. No.08/462,218, filed Jun. 5, 1995, now abandoned, which is a divisional ofapplication Ser. No. 08/089,290, filed Jul. 8, 1993, now U.S. Pat. No.5,464,449, the disclosure of which is incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a prosthetic graft and a method andapparatus for placing the graft within a body passage. In its moreparticular aspects, the invention is concerned with a resilient tubulargraft which may be reduced in diameter for delivery and then expandedinto place. The invention is especially concerned with such a graftwhich may be deployed within the thoracic aorta, the abdominal aorta, orthe femoral artery, via a groin incision.

The prior art teaches expansible tubular grafts for use in bodypassages. For example, U.S. Pat. No. 4,655,771 discloses such a graftwhich may be elongated for delivery and then expanded into place. Withthe device of that patent, the ends of the graft are held within tubularfixtures which are used to impart elongation to the graft to reduce itsdiameter during delivery. Once the graft is in place, these fixtures areremoved to release the graft for expansion. The employment of thefixtures necessarily adds to the-bulk and complexity of the mechanismand limits its use.

Another example of an expansible intraluminal graft is found in U.S.Pat. No. 4,776,337. The device of that patent is fabricated of amalleable material which is delivered in a reduced diameter conditionand, once in place, expanded by an angioplasty balloon to dilate andexpand the lumen of a blood vessel.

The prior art also teaches expansible devices for vessel dilationembodying braided cylinders of an adjustable axial length structuredsuch that a reduction in the length increases the radial size of thedevice. U.S. Pat. No. 4,572,186 shows such a device.

It is also known to provide sheaths which may be placed in vessels tofacilitate the passage of other instruments or catheters therethrough.U.S. Pat. Nos. 4,493,711 and 4,798,193 teach such devices.

SUMMARY OF THE INVENTION

The graft of the present invention is resilient and of a tubularconfiguration adapted to assume a foreshortened enlarged diametercondition upon relaxation and, upon being elongated, assume a reduceddiameter condition. The mechanism for delivery of the graft comprises anelongate placement means which extends longitudinally of the graft tocarry the graft through a body passage and facilitate its placement.Flexible lines secure opposite ends of the graft to the elongateplacement means. The lines are movable to selectively elongate the graftfor delivery, or expand the graft for placement. A retractable sheathmay be provided to shield the mechanism and graft during the deliveryprocess.

The method of the invention comprises the steps of securing oppositeends of the graft to a placement member with flexible lines, moving thelines to elongate the graft, passing the placement member through a bodypassage with the graft carried thereby in a reduced diameter elongatedcondition, and positioning the graft and releasing the lines at thedesired location. In the preferred embodiment the lines are alsoextended around the graft to subject it to radial compressionsimultaneously with its elongation.

A principal object of the invention is to provide an improved graft andsystem and method for its delivery and placement which enables the graftto be delivered through elongate body passages.

Another object of the invention is to provide an improved expansibletubular graft which may be fabricated with fluid permeable, orimpermeable, walls.

Still another object is to provide such a graft which is biocompatiblewith the body and has means to securely anchor it in place.

A further object is to provide such a graft which may be securely placedwith a main artery without blocking branch arteries, even where there isnot a substantial length of healthy artery between the aneurysm beingtreated and the branch arteries.

Yet another more general object of the invention is to provide animproved apparatus and method for intraluminal delivery of a graft to aselect remote area within a body passage, without need to surgicallyaccess the area.

Yet a further object of the invention is to provide an apparatus andmethod for the intraluminal placement of a graft within a body passagewhich may be carefully controlled to provide precise placement of thegraft and repeatedly adjusted.

Still another object related to the latter object is to provide such anapparatus and method wherein the graft can be precisely located andfully expanded before its release from the delivery system.

These and other objects will become more apparent from the followingdetailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the graft and delivery system.

FIG. 2 is an enlarged perspective view of the graft end of the deliverysystem shown in FIG. 1, with the graft in radially expanded condition.

FIG. 3 is an enlarged perspective view similar to FIG. 2, with the graftshown in a radially contracted condition.

FIG. 4 is an exploded side view of the delivery system, with parts shownin cross-section.

FIG. 5 is a side view of the delivery system and the sheath which may beused to introduce the system into an artery.

FIG. 6 is a side view of the sheath shown in FIG. 5, without thedelivery system.

FIG. 7 is a perspective view of the sheath of FIGS. 5 and 6.

FIG. 8 is cross-sectional side view of the delivery system within anartery, with the graft shown in radially contracted condition.

FIG. 9 is a cross-sectional side view, with parts thereof broken away,showing the delivery system mechanism in the process of releasing thegraft.

FIG. 10 is a cross-sectional side view showing the delivery system as ithas fully released the graft within a body passage, at the commencementof removal of the system from the passage.

FIG. 11 is a cross-sectional side view showing an artery with ananeurysm and a graft with impermeable side walls which has been placedwithin the aneurysm according the present invention.

FIG. 12 is a cross-sectional side view showing an artery having adissecting aneurysm; prior to treatment of the aneurysm through means ofthe graft of the present invention.

FIG. 13 is a cross-sectional side view of an artery corresponding tothat of FIG. 12, diagrammatically showing how the lumen of the artery isforced open through a graft placed with the present invention.

FIG. 14 is a cross-sectional side elevational view of an artery whichdoes not have a substantial length of healthy artery between itself andthe renal arteries; showing a graft placed according to the presentinvention to treat any aneurysm within the artery while permitting flowto the renal arteries.

FIG. 15 is a cross-sectional view of the body, showing the thoracic andabdominal aorta and the manner in which the system of the presentinvention can be used to deliver grafts to select areas of the aorta.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the graft and delivery system in exploded perspective, withthe graft designated by the letter G and the delivery system designatedin its entirety by letter S. The graft, as may be seen in FIG. 2, is ofan open-ended tubular configuration and comprises filaments F₁, and F₂extending helically therearound. The filaments F₁, and F₂ extend aroundthe graft in opposite directions and cross at intersections I. Thefilaments are fabricated of a resilient material, such as polyester,titanium or stainless steel. The filaments cross over each other atintersections I. As a result of the resiliency of the filaments, thegraft normally assumes a foreshortened enlarged diameter upon relaxationand, upon being elongated, assumes a reduced diameter condition (seeFIG. 3). In a typical embodiment for use in treating a dissectinganeurysm in the aorta, the graft might have the following dimensions:

ELEMENT DIMENSION Filament diameter .010 inches Graft diameter in1.0-1.25 inches the relaxed condition Graft length in the 3.0-6.0 inchesrelaxed condition

In a typical application, the graft is elongated to double its lengthfor delivery, with the result that the outside diameter of the graft isreduced by substantially more than one-half.

The components of the delivery system may best be seen from FIG. 4 andcomprise:

1. An outer tube 10 having an outer hub 12 fixed to its proximal end anda lateral opening 14 adjacent its distal end;

2. A middle tube 16 proportioned for slidable extension through theouter tube 10, said middle tube having a middle hub 18 fixed to itsproximal end and a lateral opening 20 adjacent its distal end;

3. A flexible distal retainer rod 22 proportioned for slidable extensionthrough the middle tube 16, said rod having a rod hub 24 fixed to itsproximal end;

4. A closed loop flexible line 26 fixed at one end to the hub 24 andclosed at its distal end 28;

5. A proximal suture loop retainer wire 30 proportioned for slidableextension through an opening 32 formed in one side of the hub 24 andthrough a passage 34 formed in the middle hub 18, said retainer wirehaving a retainer hub 36 fixed to its proximal end; and,

6. A looped flexible line 38 fixed at its proximal end to the hub 36 andclosed at its distal end 40.

FIG. 1 shows the delivery system in the assembled condition, with theouter hub, middle hub and rod hub exploded relative to one another forpurposes of illustration. The middle tube 16 extends slidably throughthe outer tube 10. The retainer rod 22, together with the loopedflexible line 26 extends through the middle tube 16 and the closeddistal end 28 of the line 26 extends through the opening 20 and aroundthe graft G. The wire 30, together with the looped flexible line 38,extends through the opening 32 in the hub 24 and thence through theopening 34 in the hub 18 and through the hub 12 and the outer tube 10.From the latter, it will be appreciated that there is sufficient spacebetween the outer tube 10 and the middle tube 16 to accommodate freepassage of the wire 30 and looped line 38 therethrough. The loopedflexible line 38 exits the tube 10 through the opening 14 and extendsaround the graft G.

FIG. 2 shows in detail the manner in which the looped lines 26 and 38extend around the graft G. As there shown, it will be seen that thelooped line 38 is threaded into and out of the graft around its proximalend and exits from the graft to a closed end 40 engaged around theretainer wire 30. The looped flexible line 26 is fed into and out of thegraft G around its distal end and exits therefrom, with the end 28engaged around the rod 22. Thus, with the rod 22 and wire 30 in place asshown in FIG. 2, the looped ends of the lines 26 and 38 are securedaround the distal and proximal ends, respectively, of the graft G. Inthis condition, movement of the hub 12 into mated engagement with themiddle hub 18 functions to elongate the graft G and cinch the ends ofthe looped lines around the graft, as shown in FIG. 3. Such elongationand cinching reduces the diameter of the graft by substantially morethan one-half.

From FIG. 4 it will be seen that the hubs are configured to mate onewithin the other in a nested condition. Hub 12 has a recess 42proportioned to receive a collar 44 formed on one end of the hub 18. Acollar 46 formed on the other end of the hub 18 is proportioned formating engagement within a recess 46 formed in the hub 24. The retainerhub 36 is formed with screw threads 48 formed for threaded engagementwith a threaded opening 50 in the hub 18. When the hubs are fullynested, the opening 32 is aligned with the opening 50 and the hub 36 ispassed through the opening 32 into threaded engagement with the opening50.

FIG. 5 shows the delivery system fully assembled, with the hubs nestedtogether and the graft G in the fully elongated reduced diametercondition. As there shown, the graft is in the process of beingintroduced into the femoral artery 52 through a partially split sheath54. The sheath has a length equal to or slightly greater than that ofthe delivery system and, during the delivery process, fully enclosesthat part of the system disposed within the artery. Once fully in placeat the site where it is desired to locate the graft, the sheath ispartially withdrawn, as shown in FIG. 5, to expose the graft.

FIGS. 6 and 7 show the detailed construction of the sheath. The sheathis preferably made of a flexible material having a relatively lowcoefficient of friction, such as polyethylene or TEFLON. The proximalend of the sheath, designated 56, is of an open funnel-shapedconfiguration with a slit 58 extending over its length. The distal endof the sheath, designated 60, is of a closed conical configuration witha slit 62 extending thereacross to permit the delivery system to bepassed therethrough, as shown in FIG. 5.

The graft G may be either fluid permeable or impermeable, or acombination of permeable and impermeable portions, depending upon thearea of its intended use. Permeability naturally results from thespacing of the filaments F₂. Impermeability may be provided by coatingthe graft with an elastomer, such as silicone.

Operation

The operation of the graft and delivery system may be seen from FIGS. 8,9 and 10. In FIG. 8, the graft is shown in the elongated contractedcondition, with the sheath retracted prior to expansion and release ofthe graft from the delivery system. Expansion is provided by moving thehub 12 forwardly away from the hub 18 which, in turn, moves the distalend of the outer tube 10 toward the distal end of the middle tube 16(See FIG. 9) and permits the graft to foreshorten and expand intoengagement with the artery. If the graft is not positioned at theprecise location desired, it may be re-elongated by moving the hub 12into engagement with the hub 18 and repositioned. Once the graft isexpanded at the precise location desired, it is released from thedelivery system by first withdrawing the wire 30 and the flexible line38 and then withdrawing the rod 22 and the flexible line 26. Withdrawalof the wire 30 and the rod 22 releases the looped distal ends 40 and 28of the lines. Once the lines are so released, proximal pulling of thelines (See FIG. 10) pulls the lines from the graft and out of thedelivery system. The remaining components of the system can then befully withdrawn from the artery through the groin incision. The sheath54 may be left in place to facilitate such withdrawal.

The graft may also be provided with barbs B for engagement with the bodypassage within which the graft is used. Such barbs, as shown in FIG. 2,may comprise folded-over titanium staples passed through the material ofthe graft.

FIGS. 11, 12, 13 and 14 show different applications of the graft. InFIG. 11, an impermeable coated form of the graft G is shown within anartery A₁ at the site of an aneurysm which is shielded by the graft. Thecoating on the graft is designated by the letter C. FIG. 12 shows anartery A₂ having a dissecting aneurysm 64. FIG. 13 shows the same arteryA₂ with its lumen forced open by a permeable form of the graft,designated G₁. In this application, the permeable character of the graftpermits blood to flow from the artery A₂ into the branches A₃. The arrowlines in FIGS. 12 and 13 depict the direction of the flow of blood. Asshown in FIG. 13, the graft G, compresses the aneurysm and permits freeflow through the artery. FIG. 14 shows an artery A₄ having an aneurysm66 without a substantial length of healthy artery between the aneurysmand renal arteries 68. As there shown, a graft G₂ having an impermeableportion 70 and a permeable portion 72 is used. The impermeable portion70 is positioned over the aneurysm 66 and adjacent healthy tissue andthe permeable portion 72 is placed over the renal arteries 68 andadjacent healthy tissue of the artery A₄. Thus, the graft bridges theaneurysm and the renal arteries, allowing flow through all arteries andproviding for positive graft fixation.

FIG. 15 shows the manner in which the graft may be inserted into thefemoral artery through a groin incision and directed to treat adissecting thoracic aneurysm, such as that shown in FIGS. 12 and 13, oran abdominal aortic aneurysm. Dashed lines 74 depict where the graftwould be positioned for treating a dissecting thoracic aneurysm. Dashedlines 76 depict where the graft would be positioned for treating anabdominal aortic aneurysm. Because of the side branches at the thoracicaneurysm, the permeable embodiment of FIG. 13 would be used at thatlocation. The abdominal aortic aneurysm would be treated with theimpermeable graft embodiment of FIG. 11.

CONCLUSION

From the foregoing description, it is believed apparent that the presentinvention enables the attainment of the objects initially set forthherein. In particular, a graft and delivery system is provided which maybe delivered to remote locations to treat various types of aneurysms. Itshould be understood, however, that the invention is not intended to belimited to the illustrated embodiment, but rather is defined by theaccompanying claims.

What is claimed is:
 1. A tubular graft for treating aneurysm within amajor artery wherein branch arteries extend from the major artery inclose proximity of the aneurysm and a system for placing the graftwithin an artery, said graft being fabricated of a resilient materialand adapted to reduce in diameter upon elongation, said graft and systemcomprising: a first elongate substantially fluid impermeable portionadapted to be positioned over the aneurysm so as to shield the aneurysmfrom blood flow through the major artery; a second elongatesubstantially fluid permeable portion contiguous with the first portion,said second portion being adapted to extend over the branch arterieswhen the first portion is positioned over the aneurysm, said secondportion engageable against the major artery surrounding the brancharteries to affix the position of the graft when deployed; first andsecond elongate members extending longitudinally of the graft means,said members being longitudinally movable relative to one another andthe graft means; securing means releasably attaching the elongatemembers to the tubular graft means whereby longitudinal movement of theelongate members relative to one another in one direction elongates thegraft means and longitudinal movement of the members in an oppositedirection relaxes the graft means for expansion to the foreshortenedenlarged diameter condition; and, means to selectively release thesecuring means from the elongate members.
 2. A tubular graft fortreating aneurysm within a major artery wherein branch arteries extendfrom the major artery in close proximity of the aneurysm and a systemfor placing the graft within an artery, said graft being fabricated of aresilient material and adapted to reduce in diameter upon elongation,said graft and system comprising: a first elongate substantially fluidimpermeable portion adapted to be positioned over the aneurysm so as toshield the aneurysm from blood flow through the major artery; a secondelongate substantially fluid permeable portion contiguous with the firstportion, said second portion being adapted to extend over the brancharteries when the first portion is positioned over the aneurysm, saidsecond portion engageable against the major artery surrounding thebranch arteries to affix the position of the graft when deployed;elongate placement means extending longitudinally of the graft to carrythe graft through the body passage; flexible lines securing oppositeends of the tubular graft means to the placement means; means to movesaid lines to selectively elongate the graft means; and, means toselectively release the flexible lines from the placement means.
 3. Amethod of treating an aneurysm within a major artery wherein brancharteries extend from the major artery in close promimity of theaneurysm, said method comprising: providing a tubular craft of anoutside diameter closely approximating the internal diameter of themajor artery and a length exceeding that of the aneurysm, said graftbeing fabricated of a resilient material and adapted to reduce indiameter upon elongation and having: a first elongate substantiallyfluid impermeable portion; and, a second elongate substantially fluidpermeable portion contiguous with the first portion; elongating thegraft to reduce its outside diameter to less than the internal diameterof the major artery; passing the graft into the major artery and overthe aneurysm; positioning the graft and relaxing its elongation toexpand the first portion into a condition covering the aneurysm and thesecond portion into a condition covering at least some of the brancharteries; affixing the graft within the major artery by engaging themajor artery with the second portion adjacent the at least some of thebranch arteries; extending first and second elongate members along thegraft for longitudinal movement relative to one another and the graft;securing a first end of the graft to an attachment point on said firstelongate member and a second end of the graft to an attachment point onsaid second elongate member; and moving said members longitudinallyrelative to one another to move the attachment points apart and,thereby, elongate the graft; moving said elongate members longitudinallyrelative to one another to move the attachment points together and,thereby, relax elongation of the graft and permit the graft to expandresiliently into engagement with the passage; and disconnecting thegraft from the elongate members and removing the members from thepassage.
 4. A method for treating an aneurysm within a major artery,wherein a branch artery extends from the major artery at a branchintersection, the intersection in close proximity of the aneurysm, themethod comprising: introducing a tubular vascular graft into the majorartery while the graft is in a small diameter configuration, the graftcomprising a plurality of filaments which define a perforates tubularframe, the filaments extending along a substantially fluid impermeableaxial portion of the graft and along a fluid permeable axial portion ofthe graft; positioning the fluid impermeable portion of the graft withinthe major artery in axial alignment with the aneurysm and with the fluidpermeable portion in axial alignment with the intersection; and radiallyexpanding the frame so that the filaments along the fluid permeableportion radially engage the major artery surrounding the branch arteryto anchor the graft within the major artery, the fluid permeable portionof the graft covering the branch artery such that bloodflow between themajor artery and the branch artery passes through the expanded fluidpermeable portion, the expanded fluid impermeable portion isolating theaneurysm from bloodflow through the major artery.
 5. A method as claimedin claim 4, wherein the major artery comprises the aortic artery, andwherein the fluid permeable portion covers the renal arteries.
 6. Amethod as claimed in claim 4, wherein the filaments comprise resilientstructures which resiliently engage the surrounding major artery.
 7. Amethod as claimed in claim 6, wherein the filaments comprise a resilientmaterial and extend helically around the graft in opposite directions sothat the frame expands axially when resiliently compressed radially, andwherein an elastomeric material is supported by the filaments along thefluid impermeable portion of the graft to isolate the aneurysm from thebloodflow.